The present invention relates generally to plasma processing methods and systems and more particularly, to methods and systems for having dual temperature zones on an upper electrode in a plasma chamber.
FIG. 1A is side view a typical plasma chamber 100. The typical plasma chamber 100 has a single showerhead type upper electrode 102, a substrate support 140 for supporting a substrate 130 as the substrate is being processed by a plasma 150.
FIG. 1B is a more detailed view of a typical upper electrode in the plasma chamber 100. Typically, the showerhead type upper electrode 102 includes several layers 104, 110, 120, 125. A surface layer 104 includes an exposed plasma surface 104A and multiple outlet ports 106. The exposed plasma surface 104A is the surface of the surface layer that is exposed to the plasma 150. The outlet ports are substantially evenly distributed across the plasma chamber 100 so as to maintain a uniform distribution of the process gases.
Behind the surface layer 104, is a gas distribution layer 110. The gas distribution layer 110 includes multiple gas passages 112, 114 to distribute the process gases evenly to the ports 106 across the surface layer 104. The multiple gas passages 112, 114 are coupled to one or more external process gas sources, not shown. A great amount of effort is placed in detail in the design of the multiple gas passages 112, 114 so to ensure that the multiple gas passages evenly distribute the process gases to each of the outlet ports 106 and therefore evenly throughout the plasma chamber 100.
Behind the gas distribution layer 110 is a temperature control layer 120. The temperature control layer 120 includes elements 122. Elements 122 can heat or cool the temperature control layer 120, as desired, to control the temperature of the upper electrode 102. The temperature of the upper electrode 102 is controlled as one aspect of controlling the plasma processing occurring in the plasma chamber 100. A great amount of effort is placed in the detailed design of the temperature control layer 120 so as to maintain a uniform temperature across the surface layer 104.
Unfortunately, for various reasons, the plasma processing is not always uniform across the center to edge of the substrate 130. In view of the foregoing, what is needed is a system and method of manipulating the plasma processing from the center to the edge along of the substrate 130.